Status of B-vitamins and homocysteine in diabetic retinopathy: association with vitamin-B12 deficiency and hyperhomocysteinemia

• Published in: PloS one 2011-11, Vol.6 (11), p.e26747
• Main Authors: Satyanarayana, Alleboena, Balakrishna, Nagalla, Pitla, Sujatha, Reddy, Paduru Yadagiri, Mudili, Sivaprasad, Lopamudra, Pratti, Suryanarayana, Palla, Viswanath, Kalluru, Ayyagari, Radha, Reddy, Geereddy Bhanuprakash
• Format: Article
• Language: English
• Subjects: Acids; Angiography; Blindness; Blood; Blood levels; Body mass; Body Mass Index; Body size; Cardiovascular disease; Case-Control Studies; Cross-Sectional Studies; Development and progression; Diabetes mellitus; Diabetes therapy; Diabetic retinopathy; Diabetic Retinopathy - blood; Diabetic Retinopathy - complications; Diet therapy; Dietary Supplements; Female; Fluorescein; Folic acid; Folic Acid - blood; Health risk assessment; Homocysteine; Homocysteine - adverse effects; Homocysteine - blood; Humans; Hyperhomocysteinemia; Hyperhomocysteinemia - blood; Hyperhomocysteinemia - etiology; Macular degeneration; Male; Medicine; Middle Aged; Nutrition; Prognosis; Retinopathy; Risk Factors; Type 2 diabetes; Vitamin B 12 Deficiency - blood; Vitamin B 12 Deficiency - etiology; Vitamin B Complex - adverse effects; Vitamin B Complex - blood; Vitamin B12; Vitamin B6; Vitamin deficiency; Vitamins
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0026747

Diabetic retinopathy (DR) is a common cause of blindness. Although many studies have indicated an association between homocysteine and DR, the results so far have been equivocal. Amongst the many determinants of homocysteine, B-vitamin status was shown to be a major confounding factor, yet very little is known about its relationship to DR. In the present study, we, therefore, investigated the status of B-vitamins and homocysteine in DR. A cross-sectional case-control study was conducted with 100 normal control (CN) subjects and 300 subjects with type-2 diabetes (T2D). Of the 300 subjects with T2D, 200 had retinopathy (DR) and 100 did not (DNR). After a complete ophthalmic examination including fundus fluorescein angiography, the clinical profile and the blood levels of all B-vitamins and homocysteine were analyzed. While mean plasma homocysteine levels were found to be higher in T2D patients compared with CN subjects, homocysteine levels were particularly high in the DR group. There were no group differences in the blood levels of vitamins B1 and B2. Although the plasma vitamin-B6 and folic acid levels were significantly lower in the DNR and DR groups compared with the CN group, there were no significant differences between the diabetes groups. Interestingly, plasma vitamin-B12 levels were found to be significantly lower in the diabetes groups compared with the CN group; further, the levels were significantly lower in the DR group compared with the DNR group. Higher homocysteine levels were significantly associated with lower vitamin-B12 and folic acid but not with other B-vitamins. Additionally, hyperhomocysteinemia and vitamin-B12 deficiency did not seem to be related to subjects' age, body mass index, or duration of diabetes. These results thus suggest a possible association between vitamin-B12 deficiency and hyperhomocysteinemia in DR. Further, the data indicate that vitamin-B12 deficiency could be an independent risk factor for DR.